SHIGA-TOXINS: PRE-CLINICAL ANIMAL MODEL DEVELOPMENT AND THERAPEUTIC TESTING

描述（由申请人提供）：产志贺样毒素肠出血性大肠杆菌（EHEC）菌株被认为是暴发和区域性散发血性腹泻和溶血性尿毒症综合征的最常见原因，每年涉及数千例病例和大量死亡。由于这些细菌在环境中普遍存在且感染剂量低，它们很容易以最小的复杂性传播，因此既是一个公共卫生问题，也是一个生物防御问题。来自受感染肠道的循环志贺-1和志贺-2毒素（Stx1, Stx2）是这种感染的关键毒力因素，可引起出血性结肠炎、溶血性尿毒症综合征和神经系统并发症，特别是在婴儿中。临床治疗选择主要限于强化支持，因为抗生素治疗似乎不会影响结果或疾病严重程度，实际上可能会增加细菌的毒素分泌。该合作提议旨在进一步表征志贺毒血症和溶血性尿毒症综合征的临床相关非人灵长类动物模型，并利用这些模型研究有望预防或抵消肠出血性大肠杆菌志贺样毒素致病性的新治疗方法。Stx1和Stx2毒血症的非人灵长类动物模型的持续发展将包括使用传统临床标记物和广泛的阵列方法定义生理、代谢、炎症和凝血反应。这些模型将作为临床前测试的基础：1)碳水化合物链碳硅烷树状大分子在细胞外作为毒素受体模拟物，中和循环中的毒素并防止细胞毒性；2)偶联合成蛋白激酶C肽，在细胞内中和毒素诱导的信号通路，否则会导致器官损伤。这些研究代表了五个实验室的合作努力，他们将各自独特的专业领域集中在志贺毒血症有希望的治疗方法的临床前评估上。有一些危险的大肠杆菌菌株可以感染农作物或牛，并可以通过我们的食品分配系统传播到成千上万的家庭。最近的一个例子是菠菜被大肠杆菌O157:H7菌株污染，在美国和加拿大造成两人死亡，数百人患病。这些细菌是危险的，因为它们分泌的毒素会导致严重的器官损伤，而我们没有药物可以抵消这些毒素。这项提议使用动物模型来测试新药，这些新药被预测可以有效地预防或限制细菌毒素造成的损害。

DESCRIPTION (provided by applicant): Shiga-like toxin producing enterohemorrhagic Escherichia coli (EHEC) strains are recognized as the most common cause of outbreaks and regional sporadic cases of bloody diarrhea and hemolytic uremic syndrome involving thousands of cases and numerous deaths annually. These bacteria are both a public health issue and a biodefense concern due to their pervasive presence in the environment and low infective dose, and they are easily transmitted with minimal sophistication. Circulating Shiga-1 and Shiga-2 toxins (Stx1, Stx2) from the infected gut are key virulence factors of this infection, giving rise to hemorrhagic colitis, hemolytic uremic syndrome and neurological complications, particularly in infants. Clinical treatment options are limited largely to intensive support because antibiotic therapy does not appear to influence outcome or disease severity, and may actually increase toxin secretion from the bacteria. This collaborative proposal is intended to further characterize clinically relevant nonhuman primate models of Shiga toxemia and hemolytic uremic syndrome, and to use these models to investigate novel therapeutic approaches expected to prevent or counteract the pathogenicity of the EHEC Shiga-like toxins. Continued development of the nonhuman primate models of Stx1 and Stx2 toxemia will encompass definition of the physiologic, metabolic, inflammatory, and coagulopathic responses using traditional clinical markers, as well as broad-based array approaches. These models will serve as the foundation for pre-clinical testing of 1) carbohydrate-linked carbosilane dendrimers that act extracellularly as toxin receptor mimetics to neutralize toxins in the circulation and prevent cytotoxicity; and 2) conjugated synthetic protein kinase C peptides that act intracellularly to neutralize toxin-induced signaling pathways that would otherwise lead to organ injury. These studies represent a collaborative effort of five laboratories who bring their respective and unique areas of expertise to converge on pre-clinical evaluation of promising therapeutics for Shiga toxemias. There are certain strains of dangerous E. coli bacteria that can infect crops or cattle, and can be transmitted through our food distribution system to thousands of households. One recent example is contamination of spinach with the E. coli O157:H7 strain that killed two people and caused illness in hundreds in the US and Canada. These bacteria are dangerous because they secrete toxins that cause severe organ damage and we do not have drugs that will counteract these toxins. This proposal uses animal models to test new drugs that are predicted to be effective in preventing or limiting the damage done by the bacterial toxins.